After World War I, the two countries with the largest numbers of Jews were Poland (2.8 million in 1921) and the Soviet Union (2.7 million in 1926). (See Table 1: Jewish Population by Country, 1920s-1930s) For this period numerical data are based mostly on religious affiliation as recorded in national censuses, except for the Baltic States and the Soviet Union, where they are based on ethnicity data from the censuses. Conceptually, these numbers correspond to what has been defined in Jewish demography as the “core” Jewish population. The “core” Jewish population is the aggregate of all those who, when asked, identify themselves as Jews or, in the case of children, are identified as such by their parents; it does not include persons of Jewish origin who report another ethnicity and/or religion in the census.

In the interwar period, Jewish populations increased in Poland, Romania, and the Soviet Union (especially in the Russian Federation), but remained rather stable in the Baltic States (Lithuania, Latvia, and Estonia) and Slovakia. In the same period, the Jewish populations in the Czech lands and Hungary (due to a considerable negative balance of births and deaths in the former, and a high level of apostasy in the latter), Belorussia and Ukraine (owing to mass emigration to Russia proper) decreased. By the start of World War II, Poland and the Soviet Union had about 3.3 and 3.0 million Jews, respectively. After the incorporation of eastern Poland, the Baltic States, Bessarabia, and northern Bucovina into the Soviet Union in 1939–1940, the Jewish population of the USSR reached 5.1–5.2 million by the date of the Nazi invasion, June 1941 (including an estimated 0.2–0.3 million Jewish refugees from the Nazi-occupied part of Poland).

The Holocaust caused a dramatic drop in Jewish population numbers in all the countries of Eastern Europe except Estonia, where losses were counterbalanced by large-scale immigration (see Table 2: Jewish Population by Country, 1945-ca. 2000). Subsequent emigration in the cold-war era reduced Jewish communities in Poland, Romania, and Czechoslovakia to very low numbers. The Soviet Union became the predominant country of Jewish concentration in the region. According to the 1959 census, the Soviet Jewish population reached its postwar maximum of almost 2.3 million in that year, but since the 1960s has experienced a steady decline primarily due to a negative balance of births and deaths; by 1989 there were less than 1.5 million Jews in the Soviet Union.

Since 1989, mass emigration has dramatically further decreased the number of Jews in the territory of the former Soviet Union. By about 2000, the three countries with the largest numbers of “core” Jewish population in Eastern Europe were the Russian Federation (254,000, including approximately 20,000 Jews who were possibly counted among people whose ethnicity was not recorded in the 2002 census), Ukraine (104,300 in 2001), and Hungary (52,000 in 2000).

Demographers employ another definition of Jewish population based on household data that can be empirically measured from existing statistics. This approach measures the “enlarged” Jewish population, which includes “core” Jews as well as all their household members. The spread of mixed marriage concurrent with low Jewish ethnic affiliation of the children of such marriages brought about a situation wherein the “enlarged” Jewish population is much larger than the “core” Jewish population. However, even the “enlarged” Jewish population is smaller than the total population entitled to immigration to Israel (aliyah), which includes Jews, children and grandchildren of Jews, and all their respective spouses. The estimates of the “enlarged” Jewish population do not include part of the total number of people eligible for aliyah according to the Israeli Law of Return, namely children and grandchildren of mixed marriage, all with their respective spouses, who live in households without any “core” Jewish member. In the late 1980s, the ratio of “core” to “enlarged” Jewish population in the Russian Federation was roughly 1 to 1.6, and in Ukraine and Belorussia about 1 to 1.4; on the basis of the 2002 Russian census, the ratio of “core” to “enlarged” Jewish population in the Russian Federation was estimated at approximately 1 to 1.9. At the same time, this category of Jewish population is also shrinking. For example, in the Russian Federation, the estimated number of the “enlarged” Jewish population decreased from about 1,100,000 in 1979 to 910,000 in 1989 and to almost 470,000 at the end of 2002.

Demographic Transition and Decline

The Jewish populations of Eastern Europe reached an advanced stage of demographic transition from high to low levels of mortality and fertility almost without exception earlier than the general populations in their respective countries. For example, in 1931–1932 in Poland, life expectancy reached 56.2 years for Jewish males and 59.1 years for Jewish females, whereas for the total population of the country these figures were only 48.2 and 51.4 years, respectively, and even in 1948 this indicator was lower for males in the total Polish population—55.6 years. Especially pronounced over the course of demographic transition has been the discrepancy in the levels of infant mortality between Jews and the general populations of different countries (see Table 3: Comparison of Infant Mortality Rates of Jews and General Population, per 1,000 Newborns). Polish data show that in the 1930s this most important mortality indicator of demographic transition was lower for Jewish babies by 68–69 percent. Even according to the most recent data for the Russian Federation, the much lower levels of infant mortality in the last decades of the twentieth century indicate the persistence of the very sizable discrepancy between Jews and the general population. Jews also retained their more advantaged life expectancy levels despite the fact that the most acute demographic problem in the contemporary Russian Federation has been mortality and, within the total population, males have the lowest life expectancy of all developed countries. However, for 1993–1994 the life expectancy of Russia’s male Jews was at 69.6 years, which is about the same as it was at the end of the 1980s; the discrepancy between the total male urban population and that of Jewish males has grown dramatically to about 12 years.

Earlier and prolonged fertility reduction can be ascertained based on examples of Russian and Ukrainian Jewish women for whom we have detailed census data of birth histories. Their fertility has long been too low to ensure replacement. Total Jewish fertility in the Russian Federation and Ukraine has not exceeded 1.6–1.7 children per woman in all the cohorts born since the beginning of the twentieth century. Moreover, according to the data of the 1979 and 1989 censuses, since 1919 the birth cohorts of Jewish women had a very stable and low level of fertility—about 1.4–1.5 or less (see Table 4: Fertility Indicators for Birth Cohorts of Jewish Women in the Russian Federation and Ukraine, according to Data of the 1979 and 1989 Censuses). The general population had not reached such low levels of fertility even by the end of the period. Moreover, Jewish women have much higher rates of infertility. According to the 1989 census in the Russian Federation, at ages 50–54 (after the fertile period), the share of childless Jewish women was 15.1 but only 8.5 percent for total Russian women.

Before World War II, most of the Jewish populations in Eastern Europe had a positive balance of births and deaths. In some cases (e.g., in the mid-1920s in Belorussia and Ukraine) it was even very positive (see Table 5: Balance of Jewish Births and Deaths per 1,000 Jews). During this period, crude birth rates usually decreased faster than did crude death rates (each computed per 1,000 Jews), and the positive balance diminished. Exceptions were Hungary, Romania, and Latvia, where the balance of births and deaths was about nil. However, by 1930 in Bohemia this balance was already sizably negative.

After World War II, severe aging of Soviet Jewry caused an increase in the absolute number of Jewish deaths despite the steady decrease in the numbers of this population. For example, in 1988 in the Russian Federation the absolute number of Jewish deaths was higher by 55 percent than in 1958. Inevitably, the crude death rate, which is heavily dependent on the age structure, rose to an even greater extent, and it increased between 1958–1959 and 1988–1989 from 10 to 24 deaths per 1,000 Jews. An unfavorable balance of Jewish births and deaths first occurred among Soviet Jewry in the Russian Federation, and by the 1960s these balances were negative in all the European republics.

In the 1990s, the vital crisis of (post)-Soviet Jewry intensified rapidly. In 1988–1989, Russia’s Jews had the highest negative balance of births and deaths in the Soviet Union. This was no longer true five years later: the negative balance had become greater among the Jews of Ukraine and Moldova. This change was due to the fact that the crude Jewish death rates in these states were higher than in the Russian Federation. By the mid-1990s, Jewish balances of births and deaths in the post-Soviet states were much less favorable than in West European countries.

Mixed Marriage and Its Consequences

Traditional Judaism forbids mixed marriage. Thus, the spread of mixed marriage is a good indicator of the abandonment of tradition among the Jews. Low integration into general society was seen in Poland and Lithuania between the two world wars together with almost nonexistent mixed marriage (see Table 6: Frequency of Mixed Marriage among All Registered Marriages Involving Jewish Males and Females in Designated Year). During this entire period there were also few (less than 5% of total) mixed marriages in Latvia and Slovakia. With such a low frequency of mixed marriage, its percentage among females is usually higher than among males.

During the same period, assimilation and secularization led to the spread of mixed marriage. In 1921–1925, it was at a significant level in Hungary and Bohemia, 10–11 and 20–21 percent, respectively. In the first part of the 1930s, the frequency of mixed marriage among all marriages involving Jews was as follows: in Hungary—15 percent for males and 14 percent for females; in Bohemia—31 percent for males and 26 percent for females. At this higher incidence of mixed marriage, the percentage for males was higher than that for females. The elevated frequency of mixed marriage became a very serious factor in the demographic erosion and decline of the Jewish populations in Hungary and the Czech lands.

The great increase in mixed marriage has been one of the outstanding features also among Soviet Jewry. This process actually began in the interwar period. The leading republic in this development was the Russian Federation: by the mid-1930s, among all new marriages involving Jews, 42 percent of males and 37 percent of females had married non-Jews. Ukrainian Jewry reached about the same incidence of mixed marriage only in 1978. On the eve of the start of the recent mass emigration in 1988, in the Russian Federation the frequency of mixed marriage among all marriages involving Jews was 73 percent for males and 63 percent for females.

Mixed marriage is not merely an outcome of assimilation, but is also the result of demographic realities: the shortage of Jewish marriage partners for Jewish males has, in large part, been a major cause of the spread of mixed marriage in the Soviet Union. The greatest shortage of potential Jewish brides was encountered in the Russian Federation where, according to the 1989 census, among Jews, males outnumbered females in all age groups under 60. This is naturally coincident with the character of Jewish migration. In other republics, the sex imbalance was much more moderate. Consequently, the percentage of mixed marriage was highest in the Russian Federation, and lower in the other republics. The mass emigration of the 1990s hastened the erosion of the Jewish marriage market. For example, by 1996, the frequency of mixed marriages among all marriages involving Jews in Latvia was 86 percent for males and 83 percent for females, and in Ukraine this indicator was 82 and 74 percent, respectively—levels that were much higher than those of Russia’s Jews in 1988.

After World War II in the Soviet Union, rising intermarriage was accompanied by a great increase in the proportion of children born to mixed couples. Corresponding to Russia’s high percentage of mixed marriages among Jews of the Slavic republics, the proportion of these children among all children born to Jewish mothers was greater there than in the other republics: 58 percent in 1988, or 2.1 times more than three decades earlier (see Table 7: Percentage of Children of Mixed Origin among All Children Born to Jewish Mothers in the Former USSR, by Republic, 1958-1993). Following the start of the recent mass emigration, the proportion of children born to mixed couples among all children born to Jewish mothers in 1998 reached 74 percent in Russia. In 2000 in Latvia among all children born to married Jewish females, 77 percent had fathers from other ethnic groups.

The data on the offspring of mixed couples collected during the Soviet period showed a clear preference for non-Jewish ethnic affiliation for the children. Also, according to the recent data of the 1994 Russian microcensus, non-Jewish ethnic affiliation was clearly preferable among offspring of mixed couples. For children under 16, the percentage declared Jewish was about the same regardless of the composition of the mixed couples—only 11 percent. Among offspring aged 16 and above, the percentage was even lower: 6.2 percent for couples consisting of a Jewish husband and a Russian wife, and 4.1 percent for couples consisting of a Russian husband and a Jewish wife.

Transformation of Age Structure

Transition from high to very low fertility caused a great transformation in the Jewish age composition. Changes in mortality as well as mass emigration and a high incidence of mixed marriage also affected this composition. Four stages of aging can be singled out for Jewish populations respective to the successive phases of demographic evolution (outlined mostly based on works of Roberto Bachi and Sergio DellaPergola): a pre- or early transitional stage, with very high fertility and consequently a high proportion of children under 15 (40% and above); a transitional stage, with an age distribution typical to the phase of pronounced fertility decline when the share of children ranges between 20 and 40 percent; an advanced transitional stage, prolonged fertility decline accompanied by losses from mixed marriage with the proportion of children constituting between 10 and 20 percent; and a terminal stage, the situation when the proportion aged under 15 falls to 10 percent or less, and this stage of extreme aging is concurrent with high mixed marriage and sharp numerical decline.

Different Jewish communities experienced the successive phases of demographic evolution according to their own tempo, and consequently reached the above stages of aging at different times. Between the two world wars, almost all the Jewish populations in Eastern Europe were at a transitional stage of aging (see Table 8: Distribution of Jewish Population by Age, Percent. Exceptions were the Jews of Hungary and the Czech lands who during this period reached the advanced transitional stage: in 1930, children under 15 constituted 13 percent of the total Jewish population in Bohemia, 14 percent in Moravia, and 18 percent in Hungary. By 1959, Jewish populations of the Russian Federation and Ukraine reached the same stage of aging. By 1970, Russian Jewry had already arrived at the terminal stage of aging, and by 1979, Ukrainian Jewry had also reached this stage. The 1999 census data on age composition show that after the mass emigration of the 1990s, the Jewry of Belorussia arrived at the terminal stage of aging. By 2002, about 37 percent of the Jews in the Russian Federation were aged 65 and above. Among post-Soviet countries, the share of this group grew fastest in Belorussia, from 20 percent in 1989 to 33 percent in 1999. This is indicative of the demographic collapse of these Jewish populations.